Gas springs are well known and have been used in dies of presses for sheet metal stamping operations. Gas springs commonly are used in various implementations in forming equipment to provide a moveable component or support of a forming die or a workpiece with a yielding force or a return force. For example, in a binder ring implementation, a gas spring provides a yielding force against a binder ring of a forming die to hold a metal workpiece while another part of the forming die forms, cuts, stretches, or bends the workpiece. In a lifter implementation, the gas spring provides a yielding force and return force to lift a workpiece off a surface of the forming die or to otherwise maintain control of the workpiece. In a cam tool implementation, the gas spring applies a yielding force to return a cam-activated tool to its home position. Of course, various springs including gas springs can be used in a wide range of other implementations.
Conventional gas springs usually include a cylinder, a piston disposed in the cylinder, a pressure chamber between the piston and cylinder, and various retainers and seals disposed in the cylinder to retain the piston and prevent leakage of pressurized gas from the pressure chamber. Typically, the pressurized gas provides a force on the piston to bias the piston toward an extended position and resists retraction of the piston from its extended position toward a retracted position.